The present invention relates to a stator for an electric machine as well as to a process for producing the stator. The stator is used particularly for an electric machine in a motor vehicle. The electric machine is preferably used for driving the motor vehicle.
The stator and the rotor are central components of an electric machine. Coils are placed in the stator for generating a rotating electromagnetic field, which drives the rotor. For a perfect functioning, the coils in the stator have to be electrically insulated with respect to one another. In the prior art, insulating papers, such as NOMEX paper flags, are used for this purpose. The insulation papers have to be manually placed between the coils. In addition to requiring physical effort, this process is very time-consuming particularly at the coil ends. In addition, as a result of the possible slipping of the insulation papers, considerable quality problems will occur during subsequent working steps, which require constant control and do not permit a fully automatic production process.
It is an object of the present invention to indicate a stator for an electric machine which, while the production and the assembly are cost-effective, provides an operationally secure insulation of the coil ends. Furthermore, it is an object of the present invention to indicate a method of producing a stator for an electric machine which, while the implementation is simple and process-reliable, permits an operationally secure insulation of the coil ends.
This object is achieved by means of the characteristics of the independent claims. The respective objects of the subclaims are advantageous further developments of the invention.
The object is therefore achieved by means of a stator for an electric machine. The stator comprises a cylindrical stator body having several stator slots. The stator body is produced of metal. At least three different coils for generating the electromagnetic field are situated in the stator slots. At least a first coil is provided for a first phase (U); at least a second coil is provided for a second phase (V); and at least a third coil is provided for a third phase (W). Each coil has at least one coil end at the frontal areas of the stator body. In order to insulate the individual coil ends at the respective frontal area with respect to another, a molded body is provided. In particular, one molded body respectively is provided at the two frontal areas of the stator body. The molded body is used for receiving and for electrically insulating the coil ends. For this purpose, the molded body is, for example, produced of plastic. The molded body extends in two mutually concentric ring areas. The coil end of the first coil is arranged in the first ring area. The coil end of the third coil is arranged in the second ring area. The coil end of the second coil is arranged in both ring areas. In particular, several first, second and third coils are provided. Correspondingly, there are several first, second and third coil ends. In particular, all first coil ends are arranged in the first ring area. All third coil ends are arranged in the second ring area. Correspondingly, all second coil ends are in each case arranged in the first and second ring area. The arrangement of the individual coil ends in two mutually concentric ring areas of the molded body permits a very space-saving and simultaneously secure insulation and arrangement of the coil ends.
A center axis is preferably defined at the cylindrical stator body. The center axis extends along a rotor axis of a rotor which is inserted in the stator. A radial direction is defined perpendicular to the center axis. A circumferential direction is defined around the center axis. The two ring areas of the molded body are preferably arranged concentrically with respect to the center axis. The two ring areas extend in the circumferential direction and in the radial direction. In particular, the first ring area is arranged outside the second ring area. Particularly preferably, an outside diameter of the second ring area corresponds to an inside diameter of the first ring area.
The molded body preferably has channel-shaped receiving devices for the respective coil ends. The channel-shaped receiving devices cover the respective coil end on a least three sides. Correspondingly, each receiving device has a floor. The floor extends in the radial and in the circumferential direction. Two mutually spaced side walls stand perpendicularly on the floor.
Slits are preferably formed in the channel-shaped receiving devices. These slits are aligned with the stator slots. As a result, it becomes possible to place the coils from stator slots through slits into the receiving devices.
Several coil ends of different coils of the same phase may also be placed into a single receiving device.
The first receiving devices for the first coil ends are aligned in a row along the first ring area. The third receiving devices for the third coil ends are aligned along the second ring area. The second receiving devices for the second coil ends each have a first channel-shaped section and a second channel-shaped section. The first channel-shaped section is situated in the first ring area. The second channel-shaped section is situated in the second ring area. The second receiving devices for the second coil ends therefore have a bend. This bend connects the two channel-shaped sections of the second receiving devices.
The molded body is preferably constructed of three parts. The molded body is composed of a first ring body, a second ring body and a third ring body. The individual ring bodies are each preferably produced in one piece. The individual ring bodies are, for example, produced as injection-molded parts. The first ring body preferably extends in the first ring area. The third ring body preferably extends in the second ring area. The second ring body has the second receiving devices for the second coil ends and therefore extends in both ring areas.
Furthermore, it is preferably provided that an insulation of the stator slots is integrated in the molded body. Thus, for example, projections of the molded body may engage in the stator slots and thereby insulate the stator slots with respect to the pulled-in coils.
Furthermore, the invention comprises a process for producing the just described stator. In the process, the coils are first wound outside the stator body and subsequently pulled into the stator slots and into the molded body. As an alternative, it is also provided to first place the molded body on the stator body and subsequently wind the coils directly into the stator slots and into the molded body. The advantageous further developments and subclaims described within the scope of the stator according to the invention are correspondingly advantageously applied to the process according to the invention.
Additional details, characteristics and advantages of the invention are indicated in the following description and the figures.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.